Composition of Florida-Grown Vegetables 7

content of turnip greens when grown at the same location in
different seasons. They also found a highly significant inter-
action between nitrogen, calcium and phosphorus as measured
by analysis of greens. This indicated that the change in con-
centration of 1 element in the plant could alter the concentration
of several elements. Hansen (11), working in Oregon, found
that the concentration of calcium in certain crops was highest
in August and September, lowest in winter, and intermediate
during the spring. He found that the phosphorus content varied
less than the calcium content and tended to be at its highest
concentration during the winter. Davidson and LeClerc (6)
suggested the use of ranges rather than fixed values for report-
ing the mineral content of vegetables, because of the wide ranges
that occur when plants are grown in different seasons and in
different environments.

 Methods of Sampling
 Four categories of vegetables, based on the edible portions,
were sampled. Cabbage and collards represented leaf-type vege-
tables; snap beans, the pod-type; tomatoes, the fruit-type; and
celery, the stem-type. With the exception of collards, these are
some of the most important and widely grown vegetables shipped
in quantity from Florida. Collards were collected in the North
Florida area because they represented a leafy vegetable grown
under special cultural conditions. Vegetables are often planted
following tobacco in the shade tobacco area. The crop is grown
largely by the residue of plant nutrients left in the soil after
the tobacco harvest.
 Vegetables were collected from each area as near the peak of
the harvest season as possible. It was intended that at least
8 to 10 samples be collected from each of the major producing
areas. In some areas the time of harvest was so scattered as
to limit the number of marketable samples available at 1 time.
Only marketable samples were collected. The fields selected for
sampling were chosen in a manner intended to make the data
representative of the area.
 Crop samples were taken across the rows. The line of sam-
pling usually extended from 100 to 200 feet, depending on the
size of the field. Twenty-four heads or stalks of cabbage, col-
lards or celery or about 10 pounds of beans or tomatoes were
taken from a field. Soil samples were taken from the same area
at the time of collection of vegetable samples. A stainless steel